Keep a short changelog of what you changed and why
Every time you touch an automation, write one line about what changed and why you changed it. Over time, this short list becomes the only record of decisions that would otherwise live only in your memory.
This matters because automations get patched in small ways constantly — a field gets renamed, a step gets added to handle an edge case, a delay gets shortened. Without a record, nobody remembers why those patches exist, so the next person to touch the automation either breaks something by "cleaning it up" or is too scared to touch it at all. A changelog protects both the automation and whoever has to maintain it after you. I keep mine as one running note, and I've caught myself forgetting why I set a delay a certain way more than once.
Keep it plain. A running list with the date and one sentence per change is enough — no formatting required.
Try this today: open your most-edited automation and write down the last change you remember making, even if it happened a while ago.